SIGNATURES OF RESILIENCE IN HUMAN-ALTERED COASTAL SYSTEMS

世界上超过85%的海岸线都被人类活动改变了。这些活动及其后果集中在低海拔沿海地区：海拔10米以下的沿海地带，居住着多达10亿人，在地球的有形基础设施中占有不成比例的份额。人们和基础设施沿着低洼海岸线的这种明显暴露意味着这些环境承受着沿海灾害的严重影响（例如，侵蚀、风暴潮、洪水、海平面上升）。此外，人口增长、基础设施扩张和气候变化只会使灾害影响变得更糟。随着沿海风险--定义为人类和基础设施暴露于自然灾害--的增加，科学界对沿海恢复力的兴趣也在增加，作为传统工程方法的替代方案，以保护人类改变的海岸线免受自然灾害的影响。沿海复原力的定义是沿海系统-沿海环境的物理、生态和人类组成部分，以及维持其功能的这些组成部分之间的关系-如何随着时间的推移从极端风暴等干扰中恢复过来。在低海拔海岸带的向海边缘，以海滩、沙丘、洪泛平原和湿地为特征的环境从它们吸收的风暴事件中形成了它们的物理形状。许多低洼的海岸线尽管容易遭受自然灾害，但由于人类活动，这些海岸线被广泛地建造和强烈地改变。然而，人类改变的海岸线几乎从来没有被视为动态环境本身的权利。了解人类改变的海岸线作为动态系统是至关重要的预测灾害的影响，预测气候变化的影响，并减少沿海风险。先前的工作使用计算机建模表明，与自然对应物不同，人类改变的海岸线随着时间的推移而演变，变得越来越容易受到风暴的破坏，并且在功能上依赖于工程灾害防御-因此使它们的弹性低于自然屏障。但是，人类改变的海岸线和自然海岸线如何演变的差异，以及这对它们的恢复力意味着什么，还没有通过真实的地方的观察和测量来证明和检验。该项目通过用经验证据检验理论来填补这一空白，目的是利用分析数十年卫星图像的新方法，确定和衡量世界各地人为改变的和自然的低洼沿海环境-全部位于低海拔沿海区裸露的向海边缘-的复原力指标。我将测量区分人为改变的自然海岸线的物理"签名"，将这些物理签名与沿海发展模式联系起来，并将这些信息联合收割机结合起来，以确定这些人为改变与自然海岸环境的相对"稳定性"。该项目将是第一个以这种方式量化海岸恢复力的项目，并且在这种规模下，完全来自真实的环境的观测数据。总体而言，该项目将重点关注人类改变的海岸线及其新颖的分析方法，该项目将为全球脆弱的低洼海岸环境的恢复力提供新的，以观测为驱动的见解。该项目的方法和发现将使未来的跨学科研究能够以有针对性的，高效的，有效的方式故意增强沿海恢复力，以减少沿海风险。

More than 85% of the world's coastline has been somehow altered by human activities. These activities and their consequences are concentrated in the Low Elevation Coastal Zone: a ribbon of coastal land below 10 m elevation that hosts as many as 1 billion people and a disproportionate share of the planet's physical infrastructure. Such pronounced exposure of people and infrastructure along low-lying coastlines means that these environments sustain severe impacts from coastal hazards (e.g., erosion, storm surge, flooding, sea-level rise). Moreover, population growth, infrastructural expansion, and climate change only make hazard impacts worse.As coastal risk - defined as the exposure of people and infrastructure to natural hazards - has increased, so has broad scientific interest in coastal resilience, as an alternative to conventional engineering approaches to protecting human-altered coastlines from natural hazards.Here, coastal resilience is defined as how a coastal system - the physical, ecological, and human components of a coastal environment, and the relationships among those components that sustain their functioning - recovers from disturbances, like extreme storms, over time. At the seaward edge of the Low Elevation Coastal Zone, environments characterised by beaches, dunes, floodplains, and wetlands take their physical shape from the storm events that they absorb. Despite their precarity to natural hazards, many low-lying coastlines are extensively built upon and intensively altered by human activities. However, human-altered coastlines are almost never examined as dynamic environments in their own right.Understanding human-altered coastlines as dynamic systems is essential to predicting hazard impacts, anticipating effects of climate change, and reducing coastal risk. Previous work has used computer modelling to suggest that unlike their natural counterparts, human-altered coastlines evolve over time to become increasingly vulnerable to storm damage and functionally dependent on engineered hazard defences - thus rendering them less resilient than natural barriers. But that difference in how human-altered and natural coastlines evolve, and what that means for their resilience, has not yet been demonstrated and examined with observations and measurements from real places. This project addresses that gap, by testing theory with empirical evidence.The aim of this project is to identify and measure indicators of resilience in human-altered and natural low-lying coastal settings around the world - all at the exposed, seaward edge of the Low Elevation Coastal Zone - using new methods for analysing decades of satellite imagery. I will measure the physical "signatures" that distinguish human-altered from natural coastlines, relate those physical signatures to patterns of coastal development over time, and combine that information to determine the relative "stability" of these human-altered versus natural coastal settings. This project will be first to quantify coastal resilience this way, and at this scale, derived entirely from observational data from real settings.Overall, with its focus on human-altered coastlines and its novel analytical approach, this project will deliver new, observation-driven insights into resilience in vulnerable low-lying coastal environments worldwide. The methods and findings that emerge from this project will enable future interdisciplinary research into how coastal resilience could be deliberately enhanced in targeted, efficient, effective ways to reduce coastal risk.